The present invention relates to an apparatus and a method for drying the interior of solar modules. The apparatus and the method are particularly suitable for concentrator photovoltaic (CPV) modules.
In concentrator photovoltaic modules, light irradiated by the sun is normally concentrated through lenses onto solar cells having a comparatively small surface. The solar cells are arranged on the bottom panel of a module and interconnected, whereas the lenses are arranged on a lens plate extending parallel to the bottom panel. Each solar cell has associated therewith a lens which concentrates light incident thereon onto the respective solar cell. In this connection, it is important that the distance between the lens plate and the bottom panel is maintained as precisely as possible, since defocusing would result in a deterioration of the efficiency of the solar cell module.
In principle, it would be desirable to maintain solar modules as hermetically sealed as possible so as to prevent the solar cells and the electric components in the module from being damaged by environmental influences. The situation is, however, such that the temperature of the solar cell module is under incident solar radiation much higher than would be the case without incident solar radiation. This has the effect that the internal pressure of the solar module varies strongly in accordance with the temperature-dependent expansion of the air contained in the solar module, and this would lead to a curvature of the lens plate if the module were sealed. Such a curvature would impair the focusing and, consequently, the efficiency of the module. In order to avoid such impairment, an exchange of gas is allowed between the interior of the module and the surroundings so that, if the gas should expand due to a rise in temperature, it can escape from the module. On the other hand, gas can flow into the module, when the temperature drops.
The problem arising in this connection is that, in the long run, the solar cells and electric components arranged in the solar module will be damaged by the humidity and harmful substances introduced in the solar module by the incoming air. There is a need for an apparatus and a method that can be used for removing harmful substances and moisture from a solar module and for drying the solar module.